The main objective of this project is to determine the minimal chemical and biological properties of bacterial endotoxins necessary to elicit several biologic and immunologic responses. We hope to identify, by fractionation of different endotoxins and physicochemical and biological analyses of the individual fractions, the component(s) of the macromolecular complex responsible for the antitumor effects of some endotoxins. Also, techniques are being developed to assess the cellular nature of the immunomodulatory activities of different endotoxic materials. BIBLIOGRAPHIC REFERENCES: Ribi, E., Takayama, K., Milner, K., Gray, G. R., Goren, M., Parker, R., McLaughlin, C., and Kelly, M.: Regression of tumors by an endotoxin combined with trehalose mycolates of differing structure. Cancer Immunol. Immunother. 1: 265-270, 1976.